Designing Effective Graphics Using MATLAB

The Cain Project in Engineering and Professional Communication

Linda Driskill, driskila@ruf.rice.edu

Gang Cheng, gang@rice.edu

2

The Purpose of Using Graphs

• In problem solving As part of design

As analysis of operating data

• For persuasion and interpretation Dramatize relationships

Promote identification

Make complex information accessible

3

Checklist for Good Graphics

• Purpose clear?

• Critical components defined?

• Pattern and arrangement lead eye without distraction?

• Graphic hierarchy consistent?

• Fonts legible?

• Presenter’s expertise shown?

4

Types of Graph in Matlab

• Line graph 2D 3D

• Bar graph

• Pie graph

• Ribbon graph

5

Considerations

• Purpose Problem solving? Persuasion and interpretation?

• Audience What are their background? What are they interested to know?

• Context Presentation? Report/Paper?

6

Context

• Presentation Big fonts Can use any color Can use animation

• Report Smaller fonts Often just black and white Animation impossible

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An Example

• You have: Vector 1: x[0:0.2:10]; Vector 2: sin(x); Vector 3: cos(x);

• You are asked to: Plot sin(x) vs. x and cos(x) vs. x in the same

figure; Customize the figure so that it becomes

suitable for being used in a presentation. Customize the figure so that it becomes

suitable for being used in a report/paper.

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A Simple Matlab Program

%startclear all; %clear the memoryX=[0:0.2:10]; %define the x

vectorsinx=sin(x); %calculate sin(x)cosx=cos(x); %calculate sin(x)plot(x,sinx,x,cosx); %plot the linesxlabel('x'); %add x labelylabel('y'); %add y labeltitle([‘sin and cos Functions']); %add title%end

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Default Figure Given by Matlab

0 1 2 3 4 5 6 7 8 9 10-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

x

y

sin and cos Functions

10

We Want …

• Titles and labels bigger.

• Lines thicker.

• Colors more contrasting.

• Insert Legend.

• Data points shown.

• Try adding gridlines.

11

Anatomy of a Matlab Figure

0 1 2 3 4 5 6 7 8 9 10-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

x

y

sin and cos Functionstitle

Y label

X label

Tick and tick label

lines

Axes

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Open the Property Editor

Figure Properties

13

Edit Figure Properties

Figure

Immediate apply

14

Edit Axes Properties

axes

15

Edit Line Properties

line

16

A Better-Looking Figure

0 2 4 6 8 10-1

-0.5

0

0.5

1

x

y

sin and cos Functions

17

Insert Legend

legend

18

Legend Inserted

Select object

19

Make Room for Legend

20

Edit Legend Properties

legend

21

Insert Y Grid Line

axes

Grid

Show

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Final

0 2 4 6 8 10-1.5

-1

-0.5

0

0.5

1

1.5

x

y

sin and cos Functions

sin(x)cos(x)

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Figure for Report/Paper

0 2 4 6 8 10-1.5

-1

-0.5

0

0.5

1

1.5

x

y

sin and cos Functions

sin(x)cos(x)

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Frequently Used Functions

• “plot”• “xlabel”, “ylabel”• “title”• “xlim”, “ylim”• “axis”• “legend”• “errorbar”

• Type “help function name” in Matlab command window for detailed information on the usage of the function.

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Other 2D Plotting Functions

• “loglog”: graph with logarithmic scales for both axes.

• “semilogx”: graph with a logarithmic scale for x-axis and a linear scale for y-axis.

• “semilogy”: graph with a logarithmic scale for y-axis and a linear scale for x-axis.

• “plotyy”: graph with y-tick labels on the left and right side.

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A Whole Lot More …

• 2D contour “contour” “contourslice”

• 3D plots “plot3” “mesh” “surf”

• Movie “getframe” “movie”

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Sample Movie

surfaces theallon 0.1 : B.C.

tissuet the throughou0 :I.C.

=

=

C

C

A Bioartificial Tissue Seeded

with CellsZ = 40

Z = 1

A movie created with mesh, getframe and

movie